The present invention relates to control devices of the type employing a shiftable operating handle, e.g., flow control valves used in fluid flow systems, and particularly to locking devices therefor adapted to permit selective locking of such a control device at one or more positions of its handle.
In typical conventional fluid flow systems, the selected operating position of a particular regulatory valve thereof may be essential to the proper operation and functioning of the system and the improper operation or positioning of the valve may result in the total malfunctioning of the system with attendant serious, costly and often dangerous consequences. Accordingly, it is desirable that control values be provided with some manner of locking thereof to prevent inadvertent or accidential movement of the operating handle thereof as well as intentional tampering with the handle.
A variety of lockable valves and locking devices for control valves have heretofore been proposed, examples being U.S. Pat. Nos. 1,038,308; 2,324,633; 3,156,256; 3,865,130; 3,960,168; 3,976,095; 3,980,099; 4,126,023; 4,162,690; 4,208,033; and 4,208,893. While each of these devices performs relatively satisfactorily for its intended purpose, each device suffers from one or more disadvantages. Thus, each such device is specifically designed for one particular valve or valve type, characteristically requiring either a special valve construction or the modification of one or more of the valve body, handle, and stem components in order to facilitate the proper operation of the device, and, accordingly, cannot be adapted for operation on other valves. Additionally, most, if not all, of these devices are relatively complex and are difficult and expensive to manufacture. Furthermore, certain of these devices do not prevent access to the valve stem and the nut thereon by which the valve handle is mounted thereto, whereby the effectiveness of the valve can be easily circumvented by removal or loosening of the valve handle and operation of the valve stem by another means, such as an ordinary pair of pliers.
In contrast to the above, the present invention provides a locking device of a relatively simple and inexpensive construction which may be virtually universally adapted for mounting and operation on almost all conventional control valves of the type utilizing a shiftable valve handle, and is capable of preventing access to the valve stem and nut assembly of such valves for circumvention of the intended locking function.